19 April 1991 T.I. (Tax Window, No. 2, p. 14, ¶1208)
RC will not issue a certificate unless the member's past service pension adjustment is not greater than the sum of
- the member's unused RRSP deduction room
- the member's "qualifying withdrawals" from RRSPs made for the certification, or for any previous past service pension adjustment certification made in the year
- the total of any previous certified or exempt past service pension adjustments in the year.